A Google search for “flossing the otter” turns up a song by someone named Clyde Mattocks (presumably a Jim Davis fan), and another blog that posted this same cartoon and helpfully defined “flossing the otter” as “[w]earing thong underwear backwards and sitting on the washing machine while it runs an unbalanced load.”

Given that the G-G comics are just original Garfield comics with Garfield removed, that “flossing her otter” line is straight from the brain of Jim Davis, who is probably not writing about masturbation.

Or he is always writing about masturbation. I don’t think there’s any middle ground there.